fix(web): preserve callable function properties

[kings0x]

Fixes #240

Summary

Next.js 15.5 with Turbopack transforms optional calls such as:

window.op?.('track', ...)

into a call through window.op.call(...).

The callable window.op Proxy only resolved properties from the OpenPanel
instance, so native Function properties such as .call returned undefined.

This change:

• Falls back to properties from the callable Proxy target.
• Preserves .call, .apply, .bind, and other native Function behavior.
• Handles the same behavior in the pre-load queue snippet.
• Adds regression coverage for Turbopack-style calls.
• Preserves the existing callable and property-style APIs.

Verification

Reproduced before the fix using the provided Next.js 15.5.7 Turbopack app:

Error: _window_op.call is not a function

After the fix, the same browser interaction completes without the error.

Also verified:

• 3 regression tests pass
• TypeScript typecheck passes
• Web SDK production bundle builds
• Next.js 15.5.7 production build passes
• Tests pass under the repository-pinned Node.js 24.19.0

Summary by CodeRabbit

• New Features

  • Web SDK operations can now be invoked using both callable and property-based syntax.
  • Native function helpers, such as .call, are supported when invoking SDK operations.
  • Initialization now preserves existing operation properties while continuing to queue unrecognized calls.

• Bug Fixes

  • Improved compatibility with transpiled optional-call patterns and initialization behavior.

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: defaults

Review profile: CHILL

Plan: Advanced

Run ID: 5cd70cb1-baea-4c7d-98dd-a7945a0d1f23

📥 Commits

Reviewing files that changed from the base of the PR and between 3060ca1 and 726fdf8.

📒 Files selected for processing (5)

• packages/sdks/web/src/callable.test.ts
• packages/sdks/web/src/callable.ts
• packages/sdks/web/src/init-snippet.ts
• packages/sdks/web/src/tracker.ts
• packages/sdks/web/vitest.config.ts

Included review availability: Your plan provides up to 8 included reviews per hour; 7 remain after this review.

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📝 Walkthrough

Walkthrough

The SDK adds a reusable callable wrapper for window.op, updates initialization property forwarding, replaces the tracker’s inline proxy, and adds Vitest coverage for callable and queued invocation behavior.

Changes

Callable Open Panel

Layer / File(s)	Summary
Callable wrapper and validation packages/sdks/web/src/callable.ts, packages/sdks/web/src/callable.test.ts, packages/sdks/web/vitest.config.ts	Adds createCallableOpenPanel, which supports direct calls, property calls, bound methods, and Function.prototype.call. Tests cover these invocation forms.
Initialization property forwarding packages/sdks/web/src/init-snippet.ts, packages/sdks/web/src/callable.test.ts	Existing properties now use Reflect.get in both runtime and generated initialization proxies. Unknown properties still queue calls, and q still exposes the queue.
Tracker integration packages/sdks/web/src/tracker.ts	Replaces the tracker’s inline proxy with createCallableOpenPanel(op).

Priority: ➖ Normal

Estimated code review effort: 3 (Moderate) | ~20 minutes

Change: Bug fix · Severity of issue fixed: Medium

Merge Risk: ⚪ Minimal · up to 726fd

The SDK’s callable API behavior is covered for direct, property, and transpiled Function-helper invocation paths, with no actionable merge-blocking issue identified.

🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 50.00% which is insufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff. Analyzed 2 functions across 5 files.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (4 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title clearly and concisely describes the main change: preserving native function properties on the callable web SDK proxy.
Linked Issues check	✅ Passed	The changes satisfy the coding requirements in issue #240. createCallableOpenPanel falls back to the callable target for native properties such as .call, .apply, and .bind. The pre-load snippe…
Out of Scope Changes check	✅ Passed	The changes stay within issue #240. The callable helper, tracker integration, initialization-snippet update, regression tests, and Vitest configuration all support the Proxy behavior or its verificati…

• Fix all pre-merge checks with AI

✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests

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